Manufacture of artificial silk



Patented Nov. 3, 1936 UNEE'EE STATES PATENT orr'lcr F ARTIFICIAL SILK No Drawing. Application November 23, 1934, Serial No. 754,536. In Germany November 24,

2 Claims. (01. 18-54) Our present invention relates to the manufacture of artificial silk.

One of its objects is an improved process of manufacturing artificial silk. Further objects will beseen from the detailed specification following hereafter.

The use of cellulose hydrate threads in admixture with wool is rendered difficult by the different capacity of the two fibres for being dyed.

Attempts have already been made to. overcome this difficulty by animalizing the cellulose fibres during the process of their manufacture. The process hitherto used for this animalization in the case of viscose threads consists in the addition of albuminous substances tothe spinning solution during its preparation.

This expedient does not offer a satisfactory solution of the problem. In the manufacture of viscose silk on a commercial scale the solutions are inevitably prepared a considerable time before the spinning operation, and it is hardly possible .to avoid an alkali content of more than 5 per cent. of NaOH in making such solutions In the interval between the preparation and the spinning of the solution, this concentration of alkali hydroxide decomposes the albuminous substances, so that the latter become totally or partially inefiective; moreover, uncontrollable quantities of ammonia and other decomposition products of the albuminous substances are formed in the spinning solution.

The present invention relates to'a process in which the albuminous substances are not incorporated with the alkaline (with caustic alkali or ammonia) cellulose solution until shortly before the latter is spun. Thus, the albuminous substance ls added in the spinning tank immediately before or during the de-aeration of the spinning solution; or an aibuminous solution is intermixed continuously with the spinning solution as the latter passes from the spinning tank to the spinning machine, in which case there may be used mixing devices of known type wherein thorough mixing occurs without aeration.

Albumin and casein have been found to be best for the purpose in question, but there may also be used any other albuminous substance which remains in the spun thread, that is tosay, which is of sumcientl'y high molecular weight to be insoluble in the spinning bath.

There may be added to the spinning bath substances which favour the animalization of the cellulose fibres, that is to say the capacity for being dyed by acid wool-dyestufls, owing to the presence of the albuminous substance. Substances which can be added for this purpose, particularly in the spinning of fine individual titre. are, more especially, metal salts, such as sulphate of zinc, magnesium or aluminium.

The spun fibresc'ontaining albumin can also be after-treated with formaldehyde in order to harden the albuminous substances.

The following example illustrates the-invention:

A viscose solution, ready for spinning, containing 7.5 per cent. of cellulose and. 6-7 per cent. of alkali is thoroughly mixed with an aqueous albumin'solution of 5 per cent. strength shortly before the spinning operation and while avoiding access of air, so that per 100 parts of cellulose there are about 10 parts of albumin; the mixture is at once spun in one of the usual spinning baths, for example, in a bath containing 13 per cent. of H2804 and 30 per cent. of NazSO4. Particularly in the spinning of fine titres it is advantageous to add metal salts, for example 0.5 per cent. of zinc sulphate, to the spinning bath, as'

1. In the manufacture of artificial silk or arti-'- 4 ficial spinning threads of wool-like character from alkaline cellulose solutions, particularly from viscose, by the wet-spinning process, wherein an albuminous substance of vegetable or animal origin is added, the improvement which consists in adding an amount of the albuminous substance to the solution sufiicient to impart to the eventual product an aifinity for acid wool dyestufis directly before the spinning whereby to prevent loss of afilnity for acid wool dyestufis by the resulting product.

2. In the manufacture of artificial silk or artificial spinning threads of wool-like character from alkaline cellulose solutions, particularly from viscose, by the wet-spinning process, wherein an albuminous substance of vegetable or animal origin is added, the improvement which consists in adding an am'ountof the albuminous substance to the solution suflicient to impart to the eventual product an afilnity for acid wool dyestuffs directly before the spinning whereby to prevent loss of aflinity for acid wool dyestuffs by the resulting product and after-treating the obtained fibres with formaldehyde.

'PA'OL ESSELMANN.

. KARL xtissimona. 

